(1) Field of the Invention
The present invention relates to bi-directional switches, and in particular to (A) a bi-directional switch which (i) includes a semiconductor device including Group-III nitride semiconductor and materials, (ii) is intended for protection against an inrush current, and (iii) is for use in an alternating-current two-wire switch, a switching power source circuit, and the like, (B) the alternating-current two-wire switch circuit, the switching power source, and the like that include the bi-directional switch, and (C) a method of driving the bi-directional switch.
(2) Description of the Related Art
With the recent application of inverter techniques to electric devices, inrush currents that occur at the time when such electric devices are activated may increase electromagnetic interference to nearby electric appliances and loads on the electric devices themselves. At the time of the activation, a large current flows also in a switching power source etc. in order to increase an output voltage, which increases loads on the power source component.
Patent Reference 1 (Japanese Patent Publication No. 3964912) discloses a method for reducing these inrush currents. FIG. 18 is a diagram showing a structure of a device including a bi-directional switch, a power source, and a load according to Patent Reference 1. As shown in FIG. 18, MOSFETs Q1 and Q2, diodes D1 and D2, resistors R1 to R6, capacitors C1 and C2 are inserted in a power source line. The method is intended to control resistance in the power source line by adjusting the gate voltages of the MOSFETs Q1 and Q2, and thereby reducing the amount of an inrush current.